Display screen or a portion thereof with a graphical user interface



The FIGURE is a front view of an image of a display screen or a portion thereof with a graphical user interface according to our design.

The broken line showing is included for the purpose of illustrating portions of the article and forms no part of the claimed design. The outermost dash-dot broken line illustrates a display screen or a portion thereof, and forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or a portion thereof with a graphical user interface, as shown and described. 